Multiple rabbled rotary hearth

ABSTRACT

A multiple feed for a rotary hearth calciner having a plurality of sets of rabbles arranged to engage with the materials in row form from the entrance portion of the hearth to the exit or discharge end thereof. The arrangement of the rabbles are such as to permit for the feed on to the hearth of the furnace materials of differing characteristics and to retain such differing materials in a separate state or row upon the hearth until the same are withdrawn from on to the hearth and directed to a suitable discharge or exit area. In certain instances, and where desired, the materials of one row may be caused to mix with the materials in the next adjacent row and to remain in such a mixture throughout the travel of the materials on the hearth.

United States Patent wm, Jr.

[ 1 Jan.7, 1975 [52] US. Cl 202/117, 201/40, 202/103, 202/136, 202/218 [51] Int. Cl...... Cl0b l/00, Cl0b 7/00, ClOb 31/00 158] Field of Search 202/117, 218, 217, 136. 202/103, 102; 201/40; 432/139, 121, 235; 110/13 [56] References Cited UNITED STATES PATENTS 151,640 6/1874 AB-Der-Halden 202/103 985,053 2/1911 Noad 202/103 1,878,581 9/1932 Der-Halden 202/104 3,475,286 10/1969 Kemmerer, Jr. et al 202/218 3,612,497 10/1971 Allred 201/27 Mathis 201/27 Primary Examiner-Norman Yudkoff Assistant ExaminerD. Sanders [57] ABSTRACT A multiple feed for a rotary hearth calciner having a plurality of sets of rabbles arranged to engage with the materials in row form from the entrance portion of the hearth to the exit or discharge end thereof. The arrangement of the rabbles are such as to permit for the feed on to the hearth of the furnace materials of differing characteristics and to retain such differing materials in a separate state or row upon the hearth until the same are withdrawn from on to the hearth and directed to a suitable discharge or exit area. In certain instances, and where desired, the materials of one row may be caused to mix with the materials in the next adjacent row and to remain in such a mixture throughout the travel of the materials on the hearth.

10 Claims, 8 Drawing Figures PATENTED 3,859,172

I SIEH 2% 5 'PATENTED JAN 71975 SHEET 3 OF 5 PATENTEI] JAN 71975 SHEET L 0F 5 MULTIPLE RABBLED ROTARY HEARTH BACKGROUND OF THE INVENTION Rotary hearth furnaces, per se, are not new in the art and the same have been known for years past. Normally, such a furnace comprises a rotating hearth or floor for the furnace and the same is caused to rotate at the desired speed through suitable conventional mechanisms. In furnaces of this type, there is usually provided a stationary roof structure and suitable ports for the admission into the furnace of a combustible mixture or air and a suitable exhaust for the spent gases to escape and either vent to the atmosphere or the gases collected and treated in any known manner.

In some of these prior known furnace structures, means such as roof supported rabbles are provided and these rabbles extend to a position closely adjacent to the rotary floor or hearth of the furnace for engaging the materials thereon and advancing the materials from their point of entry into the furnace to their point of discharge from within the same. In such prior furnace structures, only one point of admission of the materials to be treated in the furnace is provided and this limits to some extent the versatility of use of such a furnace, and with the above in mind, it is the main object of the invention to provide a means whereby a plurality of feed points are arranged along the rotating hearth to thus enable the feed onto the hearth materials having differing characteristics.

Another object of the invention is to provide a plurality of feed points along the outer periphery of a rotary hearth to thus permit for the feed of different materials onto the hearth and to associate rabbles with each feed point so that each of the materials fed onto the hearth will be retained in a given row from the point of entry into the furnace until the same has reached the point of discharge from the hearth.

Another object of the invention is to provide a plurality of feed points at the center of a rotary hearth and associating rabbles therewith so that the materials fed onto the hearth will be retained in a given row from the time of feed thereof until the discharge thereof at the outer periphery of the hearth.

Another object of the invention is to provide a means whereby materials fed onto the hearth in given rows are caused to become intermingled with the materials of another row and to proceed in this mingled state until the materials have been processed and are ready to be discharged from onto the hearth to a suitable receiver means located either at the center of the hearth or at points along the outer periphery thereof.

Another object of the invention is to provide a means whereby a plurality of rows of materials processed on the hearth may be simultaneously removed from thereon and directed to a suitable receiver means.

Another object of the invention is to provide a plurality of sets of roof mounted rabbles located forwardly of the points of admission of the materials fed onto the hearth so as to direct the materials on the hearth to a point of exit.

Another object of the invention is to provide a plurality of sets of roof mounted rabbles for effecting a turning over of the bed ofmaterials on a rotating hearth and to also retain the materials in distinct rows as the same are advanced from the entrance area of the furnace to the exit area thereof.

Other details, objects, and advantages of the invention will become apparent as the following description of certain present preferred embodiments thereof proceeds.

DESCRIPTION OF DRAWINGS FIG. 1 is a section taken through a rotary hearth type furnace.

FIG. 2 is a top plan view of a rotary hearth showing a plurality of sets of rabbles arranged thereover along with a plurality of admission ports for the feed of materials onto the hearth.

FIG. 3 is a section taken on line 3-3 of FIG. 2, looking in the direction of the arrows.

FIG. 4 is a top plan view showing one modification of the invention.

FIG. 5 is a modification of the inventive concept illustrated in the previous views of the drawings.

FIG. 6 is a still further modification of the arrangement of the sets of rabbles and plow employed for directing the processed materials from the hearth and to direct the same to a centrally located exit area.

FIG. 7 is a still further modification of the arrangement of the plurality of rows of the sets of rabbles and exit plow; and,

FIG. 8 is a still further modification of the arrangement of the sets of rabbles and exit plow.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings wherein like reference characters are employed to designate like parts throughout the several views of the drawings. Reference numeral 10 designates generally one type ofa furnace with which the present inventive concept could be employed in the heat treatment of materials therein. The structure shown in FIG. I of the drawings is illustrative only and not to be construed as a limitation as to the type of furnace to which the present invention may be applied. However, in order to explain generally the manner of operation of such a furnace and sets of rabbles used in conjunction therewith to carry out the objects ofthe present invention, a short description and manner of operation of such a furnace is given forthwith. The same includes a framework 11 for supporting a hearth 12 designed to be rotatably mounted on said framework 11 by means of a plurality of wheels and races 13 and 14 of conventional construction. A stationary roof 15 extends over the hearth l2 and extending through the roof are a plurality of rabbles 16. A material feed inlet is shown at 17 and a central discharge outlet is shown at 18. Suitable inlets are provided to supply a combustible mixture and/or air to support combustion within the furnace. Rotary movement of the hearth is imparted through any known comventional means. In operation, a material is fed through conduit 17 and is deposited on the floor of the hearth 12. Upon rotation of the hearth, the rabbles engage the materials thereon and advance the same towards the central discharge area where they are directed to a suitable receiver means.

Referring now to FIG. 2 to 8 of the drawings, there is shown therein a hearth 12 having an upstanding side wall 19. The hearth is made ofa suitable refractory material and is designed to rotate in the direction of the arrows.

Shown in FIG. 2 of the drawings are four sets of rabbles 16 and four admission ports 20 for the feed of materials on to the hearth. The rabbles 16 are made of a suitable refractory material and may, if desired, be cooled in any manner as by forming passages therein for the flow of a coolant therethrough. As shown more clearly in FIG. 2 of the drawings, each set of rabbles 16 are positioned in advance of the feed ports 20 for a purpose to be more fully described hereinafter. Again, referring to FIGS. 2 and 3 of the drawings, the rabbles are spaced progressively increasing inwardly of the hearth to compensate for the decrease in diameter of the hearth to thus maintain a substantially constant depth of the materials undergoing treatment on the hearth. The feed ports are located diametrically opposite one another and are formed in the roof of the furnace and may comprise suitable conduits 21 which are roof supported and which extend to a position closely adjacent the floor of the hearth. While only one such conduit 21 is shown in FIG. 3 of the drawings, it will be understood that there is provided one such conduit for each of the feed ports 20. As stated previously, the sets of rabbles are positioned in advance of the feed ports 20, and are so disposed over the hearth of the furnace as to advance the materials deposited on the hearth a short distance inwardly of the hearth and when the materials reach the next set of rabbles, the materials are again advanced a short distance inwardly of the hearth and this action repeated each time the materials contact the next rabble and so on until the materials have been moved inwardly to a position adjacent the discharge outlet for the furnace where the innermost located rabble directs the materials thereinto and on to a suitable receiver means. The arrangement of the sets of rabbles as aforesaid will retain the materials deposited on the hearth in distinct rows until such time as the same are removed from onto the hearth in the manner aforesaid. This is a considerable improvement'over prior art devices of this type inasmuch as this will permit for the charging of different materials on the hearth of the furnace and also to keep such different materials in row form without having any substantial intermingling of the materials. Thus, with an arrangement such as described above, it is conceivable that coal could be fed into one of the admission ports, and in the next succeeding admission port lime could be admitted therethrough, and at the next admission port another material of the same or differing characteristic could be fed on to the hearth of the furnace and so on until actually four different materials can be deposited on the hearth, and the four different materials simultaneously treated while undergoing travel on the hearth as aforesaid. While I have shown four admission ports 20 and four sets of rabbles in FIG. 2 of the drawings, it will be obvious that a more or lesser number of admission ports and sets of rabbles may be employed, suffice to say that any number of admission ports and sets of rabbles, over and above a single admission port, may be used in carrying out the inventive concept of the present invention. Also, the number of individual rabbles in each set of rabbles may be varied, and this will be dependent primarily upon the diameter of the hearth and possibly upon the nature of the materials undergoing treatment on the hearth. The structure shown in FIGS. 2 and 3 show a discharge opening 18 which may be in the nature of the exit opening 18 shown in FIG. 1 of the drawings although this feature of the structure forms no part of the present invention.

Referring now to FIG. 4 of the drawings, there is shown therein an arrangement similar to that described with reference to FIGS. 2 and 3 of the drawings only in this form of the invention only two sets of rabbles 16 are positioned in advance of the two admission ports 20. The structure shown in this form of the invention is designated to operate in the same manner as that previously described with reference to FIGS. 2 and 3 ofthe drawings aforesaid.

FIG. 5 of the drawings shows an arrangement of the sets of rabbles l6 and admission ports 20 similar to that described in connection with FIGS. 2 and 3 of the drawings, except that in this case, the spacing between some of the rabbles in each set of rabbles may be spaced a greater distance from the next adjacent rabble. This arrangement of the rabbles may be desirable in the treatment of certain materials on the hearth. Also, shown in FIG. 5 of the drawings, guide baffles 22, 23 are arranged downwardly of admission ports 20. Guide baffles 22, 23 are roof supported as described previously and are so disposed over the hearth 12 as to combine in one row a pair of rows of materials which have already been deposited on the hearth. Such an arrangement of the guide baffles will be employed when it is desired to combine in one row, a pair of adjacent rows of materials, usually materials differing in certain characteristics and to permit the combined materials to proceed on to the hearth and to be processed simultaneously. While I have shown but one set of guide baffles 22, 23, it is obvious as many sets of such guide baffles may be employed asare required to combine additional rows of materials on the hearth. Shown in FIG. 5, of the drawings, the baffles 22, 23 combine but two separate rows of materials to a single row. Obviously, should it be desired to combine more than two rows of materials, baffles of a width capable of spanning more than two rows of materials could be employed to achieve this result.

Shown in FIG. 6 of the drawings is an arrangement for the removal of the materials on the hearth and directing the same to a centrally located exit area 18. Plows 24, 25 are arranged to extend over the hearth l2 and are of sufficient width to span an area wide enough to cover more than one row of materials on the hearth. The plows 24, 25 are so disposed over the hearth area as to direct the materials to the central outlet 18. 7

FIGS. 7 and 8 show a still further modification of the invention. In both of these figures of the drawings, the materials to be processed on to the hearth area are fed thereto by means of centrally located feed ports 20 and sets of rabbles 16 direct the materials outwardly in rows to suitable outlet means. The structure shown in FIG. 7 provides for four feedinlets 20 and four outlet areas 26 which are located along the outer periphery of the hearth area 12. The outermost rabble in each set of rabbles directs the materials to the outlet areas and to suitable receiver means for the processed materials.

FIG. 8 of the drawings show but two centrally located feed ports 20 and two sets of rabbles 16 which are positioned in advance of the feed ports. The rabbles are designed to move the materials outwardly of the central inlet ports in row form. A plow member is positioned adjacent the outlet 26 and directs the materials outwardly from the hearth to a suitable receiver means. The plow 24 shown in this figure of the drawings is designed to remove a plurality of rows of processed materials simultaneously from the hearth.

The above description of the invention defines the various components employed in carrying out the objects of the invention. Essentially, the inventive concept is predicated upon the ability to simultaneously process on one rotary hearth a plurality of different materials and, when desired, the materials are kept in distinct rows on the hearth from the entrance to the exit area of the hearth or, when it is desirable that one row of materials on the hearth be mixed with another row of materials, provision is made for the intermingling of the said materials.

From the above description of the invention, it will readily be apparent that the present inventive concept provides for a wide range of use of a conventional rotary hearth structure in the processing of materials thereon.

It should be pointed out that the inventive concept described above can be employed in the processing of materials on a hearth such as coal, lime, or any other carbonaceous materials which yield volatiles when subjected to a heat treatment although the invention is not necessarily limited to the treatment of such materials. Actually, the inventive concept can be applied to the processing in any manner, any materials deposited on a hearth where it is desired to cause said materials to travel in rows from the entrance to the exit area adjacent the hearth and where it is desired to provide for the feed of different materials on to the hearth.

While in the foregoing the preferred embodiment of the invention has been described and shown, it is understood that alterations and modifications may be made thereto provided that the said alterations and modifications fall within the scope of the apended claims.

What is claimed is:

l. A multiple rabble arrangement for a furnace enclosure comprising a roof and side walls and a horizontally disposed flat hearth mounted for rotation within said furnace enclosure and wherein a plurality of rows of materials deposited onto said hearth are maintained in distinct rows from time of deposit onto and time of exit of said materials from onto said hearth, while advancing the distinct rows from feedport to outlet, a plurality of opposed sets of feedports for the feed of materials onto the said hearth, a plurality of diametrically opposed sets of rabbles mounted in the roof of said furnace enclosure and extending to a position in close proximity to the said rotary hearth, said sets of rabbles maintaining said rows of materials in distinct rows on the said hearth, while simultaneously advancing said distinct rows of materials progressively from the said feedports to the outlets, the feedports and the outlets being disposed, respectively, in the periphery and center of the hearth in opposed relationship.

2. The structure recited in claim 1 wherein said feed ports are positioned along the outer periphery of said rotary hearth.

3. The structure recited in claim 1 wherein said sets of rabbles are mounted in advance of the said feed ports.

4. The structure recited in claim 1 wherein said feed ports are located centrally of said rotary hearth.

5. The structure recited in claim 1 wherein guide baffles are interposed between the sets of rabbles to combine the materials in different rows into a single row.

6. The structure recited in claim 1 wherein said discharge outlets are positioned along the outer periphery of said rotary hearth.

7. The structure recited in claim 1 wherein said discharge outlets are located centrally of said rotary hearth.

8. The structure recited in claim 1 wherein a plurality of rows of materials are simultaneously discharged from on to the hearth.

9. The structure recited in claim 1 wherein each of the rabbles in said sets of rabbles are spaced progressively increasing inwardly towards the center of said hearth.

10. The structure recited in claim 1 wherein each of the rabbles in said sets of rabbles are spaced progressively increasing outwardly towards the outer periphery of said hearth. 

1. A multiple rabble arrangement for a furnace enclosure comprising a roof and side walls and a horizontally disposed flat hearth mounted for rotation within said furnace enclosure and wherein a plurality of rows of materials deposited onto said hearth are maintained in distinct rows from time of deposit onto and time of exit of said materials from onto said hearth, while advancing the distinct rows from feedport to outlet, a plurality of opposed sets of feedports for the feed of materials onto the said hearth, a plurality of diametrically opposed sets of rabbles mounted in the roof of said furnace enclosure and extending to a position in close proximity to the said rotary hearth, said sets of rabbles maintaining said rows of materials in distinct rows on the said hearth, while simultaneously advancing said distinct rows of materials progressively from the said feedports to the outlets, the feedports and the outlets being disposed, respectively, in the periphery and center of the hearth in opposed relationship.
 2. The structure recited in claim 1 wherein said feed ports are positioned along the outer periphery of said rotary hearth.
 3. The structure recited in claim 1 wherein said sets of rabbles are mounted in advance of the said feed ports.
 4. The structure recited in claim 1 wherein said feed ports are located centrally of said rotary hearth.
 5. The structure recited in claim 1 wherein guide baffles are interposed between the sets of rabbles to combine the materials in different rows into a single row.
 6. The structure recited in claim 1 wherein said discharge outlets are positioned along the outer periphery of said rotary hearth.
 7. The structure recited in claim 1 wherein said discharge outlets are located centrally of said rotary hearth.
 8. The structure recited in claim 1 wherein a plurality of rows of materials are simultaneously discharged from on to the hearth.
 9. The structure recited in claim 1 wherein each of the rabbles in said sets of rabbles are spaced progressively increasing inwardly towards the center of said hearth.
 10. The structure recited in claim 1 wherein each of the rabbles in said sets of rabbles are spaced progressively increasing outwardly towards the outer periphery of said hearth. 